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Math Help - Permutations Problems

  1. #1
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    Permutations Problems

    How many different telephone numbers are possible if they must have atleast one '3' and two '7's?
    it is a 7 digit phone number.
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  2. #2
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    Re: Permutations Problems

    What is the length of the phone number in question?
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  3. #3
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    Re: Permutations Problems

    there are 7 digits in the phone number
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  4. #4
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    Re: Permutations Problems

    Well here are the combinations


    X represents the variable which is 1,2,4,5,6,8,9,0.

    773XXXX
    7733XXX
    77333XX
    773333X
    7733333
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  5. #5
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    Re: Permutations Problems

    so the permutations would be 7!/2!
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